2019130620198551530FF85BB39-FFF9-FFEE-7E00-5733FF94AF1D3251198C49C3051-28BD-46A8-A5AB-E33C3A0DD9DD0803201910052019Wan-Jin Chang, Fengyuan Li, Shuqiang LiThis is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Abstract

Three new species of the genus Flexicrurum Tong & Li, 2007, from Hainan Island, China are described: F.wuzhishanensesp. nov. (♂♀), F.yangjiaosp. nov. (♂♀), and F.qishisp. nov. (♂♀). A key to males of species of Flexicrurum is provided. Additionally, the female of F.minutum Tong & Li, 2007, is described for the first time. To date, the genus is endemic to Hainan Island, China. Types are deposited in the Institute of Zoology, Chinese Academy of Sciences (IZCAS) in Beijing.

The spider family Psilodercidae Machado, 1951, was only recently elevated to family rank from a subfamily of Ochyroceratidae Fage, 1912. This taxonomic rearrangement is based on the presence of book-lungs, the position of tracheal stigma, the number of promarginal cheliceral teeth, the shape of the labium, and the point of attachment of the bulbus (Wunderlich 2004, 2008).

Prior to this study, only three species from the genus Flexicrurum Tong & Li, 2007, have been described (Tong and Li 2007): F.flexicrurum, F.longispina, and F.minutum. These species are confined to Hainan Island, China, and have been the only representatives of the genus (World Spider Catalog 2019).

While studying new material collected in Hainan Island, we recognized the matched pairs of three new species of Flexicrurum, and a hitherto unknown female of F.minutum, one of the three species described by Tong and Li (2007). This paper describes all of these new discoveries by providing images of their genital organs and close-up photos of their chelicerae.

Materials and methods

Types are deposited in the Institute of Zoology, Chinese Academy of Sciences (IZCAS) in Beijing. All specimens collected were observed and preserved in 95% ethanol. The specimens were measured and examined under a Leica M205 C stereomicroscope, and further morphological details were observed with an Olympus BX41 compound microscope. The left male palp was detached for closer examination. Carapace measurements include the clypeus. The internal genitalia and male bulb were dissected and immersed in lactic acid. An Olympus C7070 wide zoom digital camera (7.1 megapixels) mounted on an Olympus SZX12 stereomicroscope was used to take photos. Photos were stacked with Helicon Focus 6.7.1 to generate images with extended depth of field. The images were post-processed with Adobe Photoshop. Leg measurements are shown as total length (femur, patella, tibia, metatarsus, and tarsus). Leg segments were measured from the retrolateral side. All measurements are given in millimetres (mm). Terminology follows that of Li et al. (2014), Tong and Li (2007) and Deeleman-Reinhold (1995). Coordinates of collecting locations were recorded in Microsoft Excel and imported into ArcGIS 10.2 to generate a map which was subsequently exported to Adobe Photoshop CC 2014 for further editing. The following abbreviations are used in text: ALE anterior lateral eye, ME median eye, PLE posterior lateral eye.

The species name is an adjective referring to the type locality; the Chinese pinyin “wǔ zhǐ” means five fingers, and “shān” means mountain. The name is a graphic interpretation of contour of the mountain ranges with a striking resemblance to five fingers.

Diagnosis.

Flexicrurumwuzhishanense sp. nov. strongly resembles F.qishi sp. nov. Males of F.wuzhishanense sp. nov. can be distinguished by a longer bulbal apophysis (Fig. 2D) (vs shorter bulbal apophysis in F.qishi sp. nov.), the bulbal apophysis which is further from embolus (Fig. 2B) (vs bulbal apophysis and embolus nearer each other (Fig. 6B), simple protruded conductor comprises only a single part (Fig. 2B) (vs a rather slender conductor comprising two parts, resembling a broken ring in F.qishi sp. nov. (Fig. 6A, B)), the bulb with scattered black spots (Fig. 2A) (vs absence of scattered black spots on bulb of F.qishi sp. nov. (Fig. 6A)); females can be distinguished by a rather broad dome-shaped epigastric area (Fig. 1B) (vs a rather plump, triangular epigastric area in F.qishi sp. nov. (Fig. 5B)), spermathecae can be distinguished by a pair of lobed ducts laterally connected with bow-tie-shaped spermathecae (Fig. 1A) (vs a pair of spermathecae resembling the structure of a human uterus in F.qishi sp. nov. (Fig. 5A)).

The species name is a noun in apposition derived from the word for “goat horn” in Chinese pinyin “yángjiǎo”. It refers to the shape of the conductor which curves strongly inwards, like a goat horn.

Diagnosis.

Flexicrurumyangjiao sp. nov. can be distinguished from F.wuzhishanense sp. nov. and F.qishi sp. nov. by a posterolateral cymbial apophysis with a single tip or bulge (Fig. 4D) (vs a posterolateral cymbial apophysis with two bulges or protuberances (i.e., a divided tip) in F.wuzhishanense sp. nov. and F.qishi sp. nov.), a pointed embolic end (vs hook-liked embolic end in F.wuzhishanense sp. nov. and F.qishi sp. nov.), a shorter laminar apophysis (vs longer in F.wuzhishanense sp. nov. and F.qishi sp. nov.), and the position of the entire bulb is opposite that of the other two species—the laminar apophysis is parallel to the tip of cymbial protrusion (vs laminar apophysis and tip of cymbial protrusion not parallel in F.wuzhishanense sp. nov. and F.qishi sp. nov.).

The species name is a noun in apposition derived from the Chinese pinyin “qíshì” (knight) and refers to the ventral view of the bulb which resembles a piece in international chess game representing a knight (Fig. 6A).

Diagnosis.

The species is similar to Flexicrurumwuzhishanense sp. nov. Diagnostic features are discussed under F.wuzhishanense sp. nov.

The female was matched with the holotype male on the basis of proximity of its collection location to the type locality (only about 30 km away), similarities in somatic morphology with the holotype male, and from DNA barcoding data.

Acknowledgements

The manuscript benefitted greatly from comments by Drs Abel Pérez-González and Jie Liu. Sarah Crews and Joseph K. H. Koh kindly improved the English of the text. This study was supported by the National Natural Sciences Foundation of China (NSFC–31530067).

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